Variable Syndromic Immunodeficiency in Patients with Biallelic PRIM1 Mutations.

Mutations in genes of the DNA polymerase complex have been linked to impaired immunological function next to distinct syndromic features. Biallelic mutations in PRIM1 are associated with a primordial dwarfism syndrome with variable hypogammaglobulinemia. The disease is mostly lethal in infancy due to pulmonary infections as well as hepatic cirrhosis. We studied 3 novel patients with PRIM1-deficiency with a focus on immunological consequences. All three shared dysmorphic features including a prominent forehead, triangular face and bilateral cryptorchidism. P1 carried the novel homozygous PRIM1 splice variant c.103+2T>G, allowing residual protein expression and associated with a mild clinical phenotype. P2 and P3 carried the known homozygous variant c.638+36C>G and died in infancy. Paradoxically, B cell lymphopenia was most pronounced in P1. No other significant lymphocyte abnormalities were detected. Interestingly, all 3 patients showed variable, but intermittently excessive Type I interferon signatures. In summary, the B-cell deficiency in PRIM1-deficiency is markedly variable and the severity of syndromic manifestations is not predictive of the immunological phenotype. We highlight a potential contribution of pathological type I interferon activation to disease pathogenesis which warrants further investigations.

Variable Clinical Courses of Varicella Zoster Virus Infection-related or Vaccination-related Bone Marrow Failure.

We report 5 children with bone marrow failure (BMF) after primary varicella zoster virus (VZV) infection or VZV vaccination, highlighting the highly variable course. Two patients were treated with intravenous immunoglobulins; one had a slow hematologic recovery, and the other was rescued by allogeneic hematopoietic stem cell transplantation (HSCT). Of the 2 patients treated with immunosuppressive therapy with antithymocyte globulin and cyclosporine, one had a complete response, and the other was transplanted for nonresponse. One patient underwent a primary allograft. All patients are alive. This study demonstrated that VZV-associated BMF is a life-threatening disorder that often requires HSCT.

Autoimmune lymphoproliferative immunodeficiencies (ALPID) in childhood: breakdown of immune homeostasis and immune dysregulation.

Many inborn errors of immunity (IEI) manifest with hallmarks of both immunodeficiency and immune dysregulation due to uncontrolled immune responses and impaired immune homeostasis. A subgroup of these disorders frequently presents with autoimmunity and lymphoproliferation (ALPID phenotype). After the initial description of the genetic basis of autoimmune lymphoproliferative syndrome (ALPS) more than 20 years ago, progress in genetics has helped to identify many more genetic conditions underlying this ALPID phenotype. Among these, the majority is caused by a group of autosomal-dominant conditions including CTLA-4 haploinsufficiency, STAT3 gain-of-function disease, activated PI3 kinase syndrome, and NF-κB1 haploinsufficiency. Even within a defined genetic condition, ALPID patients may present with staggering clinical heterogeneity, which makes diagnosis and management a challenge. In this review, we discuss the pathophysiology, clinical presentation, approaches to diagnosis, and conventional as well as targeted therapy of the most common ALPID conditions.